OK, now I have to chime in (six years late?) with my GT kitty story.
He used to open a louvered window to get out of the house when we were trying to make him an indoor cat. We had no idea how he was getting out - everything would be closed up, then he'd be outside. By pulling on the louvers he could open it enough to slip out, then the weight of the louvers would close the window again. (We discovered this when we tightened up the screens and he got stuck between the window and the screen one morning.)
He also found a peer kitty. The friend taught him to come over and visit at the other cat's house. They played together every day. Mine had a particular scratch at our front door to come in; one day we heard it, but DK was on the rug. He answered the door and went out to play.
